New Innovations in Mechanical Lithotipsy
New advances in combination-energy lithotrite technology have also been made over the past few years. This class of devices have long been relied upon during percutaneous nephrolithotomy (PCNL) to break and remove large stone volumes relatively quickly. As with many other endourologic devices, these tools have evolved significantly since their initial introduction as single-energy devices in the 1950s (ultrasonic[27]) and 1990s (ballistic[28]). A critical turning point in the evolution of these devices came in the early 2000s with the combination of energy modalities into a single dual-probe device – the Swiss LithoClast Master (EMS, Nyon, Switzerland) – which contained a solid air-driven pneumatic probe within the lumen of a larger, hollow ultrasonic probe and simultaneously possessed suction capability.[29] The new combination device demonstrated superior fragmentation efficiency and lithotripsy speed compared with contemporary single-energy devices.[30,31] The drawback of this device was that, with the pneumatic probe (1-mm diameter) in place within the lumen of the ultrasonic probe (2.8-mm inner diameter), suction evacuation efficiency was significantly attenuated, and the maximum suctionable fragment diameter was reduced to 0.9 mm.
Subsequent combination-energy devices were developed which combined ultrasonic and ballistic energy – the CyberWand (Olympus, Shinjuku, Tokyo, Japan) and the ShockPulse (Olympus) – both of which utilize piezoelectric elements to produce ultrasonic effects but differ from the Swiss LithoClast in their mechanism for generating ballistic energy. Specifically, the ShockPulse is a single hollow probe design which delivers ultrasonic vibrations at a frequency of 21 kHz but which also contains a free mass with a return spring at the probe base within the handle. As the ultrasonic energy passes through the probe, oscillations of the free mass with the spring produce ballistic energy at a rate of 300 Hz. Early benchtop studies of the ShockPulse system demonstrated good efficacy of the device and commented favorably on the large probe lumen and ergonomic hand controls.[32]
In 2018, the Swiss LithoClast Trilogy (EMS) was introduced into the market. The Trilogy is a combination-energy, single-probe device with in-unit suction capability. The system is notable for its novel electromagnetic mechanism of producing ballistic energy. While previous generation devices have relied on a variety of mechanisms for the production of ballistic energy, such as an internal pneumatically driven projectile (Swiss LithoClast Master) or oscillating free mass with return spring (ShockPulse), the Trilogy's electromagnetic propulsion mechanism is unique in that it produces a high degree of probe tip displacement to deliver ballistic energy but does not occupy space within the hollow single-probe lumen. This ability to deliver highly effective ultrasonic and ballistic energy simultaneously without compromising suction capability has been shown to translate into excellent stone clearance rates relative to the older generation LithoClast devices on the benchtop.[33] It remains to be seen whether the Trilogy can demonstrate these benefits over its comparators in the clinical setting, although one recent, prospective, multiinstitutional study of initial clinical experience with the Trilogy found it to be highly efficacious and safe.[34]
Curr Opin Urol. 2020;30(2):144-148. © 2020 Wolters Kluwer Health, Inc.
